Stator unit, motor, and method of manufacturing stator unit

ABSTRACT

A stator unit included in a motor includes a base member, an armature, a circuit board, and a mold resin portion. The base member extends substantially perpendicularly to a vertically extending center axis. The armature and the circuit board are positioned above the base member. The circuit board is electrically connected to the armature. The mold resin portion covers the armature and the circuit board. In a process of forming the mold resin portion, the base member is supported by a first mold. Then, the first mold is joined to a second mold such that a cavity is provided therebetween. In this step, the second mold is pressed against a projection provided on an upper surface of the base member and on a radially outer side with respect to the circuit board in plan view. The projection thus pressed is squashed. Subsequently, molten resin is injected into the cavity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2016-240081 filed on Dec. 12, 2016. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates to a stator unit, a motor, and a methodof manufacturing a stator unit.

2. Description of the Related Art

A known so-called molded motor includes a mold resin portion that coversa stator. Such a molded motor has excellent waterproofness and excellentcharacteristics in suppressing vibration and sound that are generatedwhen the motor is driven. In particular, the molded motor is configuredsuch that the mold resin portion prevents water drops from enteringareas where electrical elements such as coils of the stator areprovided. An exemplary molded motor is disclosed by Japanese Laid-openPatent Application Publication H06-178484.

In a step of forming the mold resin portion, an assembly including astator and a base member that supports the stator is placed between apair of molds. Then, molten resin is injected into a cavity providedbetween the pair of molds. In this step, part of the base member is heldbetween the pair of molds. Therefore, if the fastening pressure appliedto the pair of molds is too high, the base member may be damaged withthe load applied from the molds.

The present disclosure provides a structure configured such that a basemember is prevented from being damaged under a load applied from moldsin a step of forming a mold resin portion. The present disclosure alsoprovides a method of manufacturing such a structure.

SUMMARY OF THE INVENTION

According to an exemplary embodiment of the disclosure, there isprovided a stator unit included in a motor. The stator unit includes abase member extending substantially perpendicularly to a center axisextending vertically, an armature positioned above the base member, acircuit board positioned above the base member and electricallyconnected to the armature, and a mold resin portion covering thearmature and the circuit board. The base member has a projectionresultant on a radially outer side with respect to the circuit board inplan view.

According to another exemplary embodiment of the disclosure, there isprovided a method of manufacturing a stator unit that includes a basemember extending substantially perpendicularly to a center axisextending vertically, an armature and a circuit board both positionedabove the base member, and a mold resin portion covering the armatureand the circuit board. The method includes a) supporting the base memberby a first mold, b) joining the first mold to a second mold such that acavity is provided between the first mold and the second mold, and c)injecting molten resin into the cavity. In step b), the second mold ispressed against a projection, the projection being provided on an uppersurface of the base member and on a radially outer side with respect tothe circuit board in plan view.

According to the above exemplary embodiments of the disclosure, in astep of forming the mold resin portion, the second mold is pressedagainst the projection provided on the upper surface of the base member,whereby the projection is squashed. Thus, the load applied to the basemember is reduced. Consequently, the occurrence of damage to the basemember under the load applied from the mold is suppressed.

The above and other elements, features, steps, characteristics andadvantages of the present disclosure will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view of a motor according to anembodiment.

FIG. 2 is a flow chart illustrating a process of forming a mold resinportion.

FIG. 3 illustrates a state in the process of forming the mold resinportion.

FIG. 4 illustrates another state in the process of forming the moldresin portion.

FIG. 5 illustrates yet another state in the process of forming the moldresin portion.

FIG. 6 is a vertical sectional view of relevant part of the motor andillustrates a base member, a circuit board, a first mold, and a secondmold.

FIG. 7 is another vertical sectional view of the relevant part of themotor and illustrates the base member, the circuit board, the firstmold, and the second mold.

FIG. 8 includes a top view and a vertical sectional view of the basemember.

FIG. 9 is a vertical sectional view of relevant part of a motoraccording to a modification.

FIG. 10 includes a top view and a vertical sectional view of a basemember according to the modification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An exemplary embodiment of the present disclosure will now be describedwith reference to the drawings. Herein, a direction parallel to thecenter axis of a motor including a stator unit is defined as “the axialdirection,” a direction orthogonal to the center axis of the motor isdefined as “the radial direction,” and a direction in which a circulararc around the center axis of the motor extends is defined as “theperipheral direction.” Furthermore, the shapes and relative positions ofindividual elements will be described on the premise that the axialdirection corresponds to the vertical direction, and a side of a basemember that is nearer to an armature is defined as the upper side. Notethat the definition of the vertical direction does not limit theorientation of the motor according to the present disclosure in themanufacturing process and in the state of use.

FIG. 1 is a vertical sectional view of an axial-flow fan 100 including amotor 1 according to an embodiment of the present disclosure. Theaxial-flow fan 100 is used as, for example, an apparatus for supplying aflow of cooling air in a communication base station equipped with aplurality of electronic devices. Note that the stator unit and the motoraccording to the present disclosure may alternatively be applied toother appliances such as home appliances and onboard components.

Referring to FIG. 1, the motor 1 includes a stator unit 2 and a rotorunit 3. The stator unit 2 is fixed to a frame of an apparatus to whichthe motor 1 is provided. The rotor unit 3 is supported by an upperbearing 26 and a lower bearing 27 in such a manner as to be rotatablerelative to the stator unit 2.

The stator unit 2 includes a base member 21, a bearing housing 22, astator 23, a circuit board 24, and a mold resin portion 25.

The base member 21 is provided below the stator 23 and extendssubstantially perpendicularly to a center axis 9. The base member 21 ismade of resin. The base member 21 is connected to a cylindrical casing(not illustrated) with a plurality of ribs interposed therebetween. Thecylindrical casing provides a wind tunnel of the axial-flow fan 100. Thebase member 21, the plurality of ribs, and the casing may be integratedtogether as a single member or may be provided as separate members.

The base member 21 according to the embodiment includes a disc portion211, an inner wall portion 212, and an outer wall portion 213. The discportion 211 extends annularly around the bearing housing 22 andperpendicularly to the center axis 9. The inner wall portion 212 has anannular shape and projects upward from a radially inner end of the discportion 211. The inner wall portion 212 is fixed to the outer peripheralsurface of the bearing housing 22. The outer wall portion 213 has anannular shape and projects upward from a radially outer end of the discportion 211.

The bearing housing 22 is a cylindrical member extending verticallyalong the center axis 9. The bearing housing 22 is positioned on theradially inner side with respect to the base member 21, the stator 23,and the circuit board 24 and on the radially outer side with respect tothe upper bearing 26 and the lower bearing 27. The bearing housing 22 ismade of metal such as brass or iron. The lower end of the bearinghousing 22 is fixed to the inner periphery of the base member 21.

The base member 21 is obtained by injecting molten resin into a mold inwhich the bearing housing 22 is placed in advance and then curing theresin. That is, the base member 21 is a molded resin componentintegrated with the bearing housing 22 by injection molding. The basemember 21 is fixed to the bearing housing 22 when molded. Note that thebase member 21 may be fixed to the bearing housing 22 by another methodusing adhesive or the like.

While the embodiment is described on the premise that the bearinghousing is made of metal and the base member is made of resin, thepresent disclosure is not limited to such an embodiment. Specifically,the bearing housing and the base member may be integrated together intoa single resin member. In such a case, the number of components issmaller than in the case where the bearing housing and the base memberare provided as separate members, and the productivity is thereforeincreased.

The stator 23 is an armature that generates a rotating magnetic fieldcorresponding to the driving current thereof. The stator 23 ispositioned above the base member 21 and the circuit board 24 and on theradially outer side with respect to the bearing housing 22. The stator23 includes a stator core 41, an insulator 42, and a plurality of coils43. The stator core 41 is formed of lamination steel that is a magneticbody. The stator core 41 includes a core back 411 having an annularshape, and a plurality of teeth 412. The inner peripheral surface of thecore back 411 is fixed to the outer peripheral surface of the bearinghousing 22. The teeth 412 each projects radially outward from the coreback 411.

The insulator 42 is attached to the stator core 41. The upper surface,the lower surface, and the two side surfaces, in the peripheraldirection, of each of the teeth 412 are covered with the insulator 42.The insulator 42 is made of resin, which is an insulating material. Thecoils 43 are each formed of a conducting wire wound around acorresponding one of the teeth 412 with the insulator 42 interposedtherebetween. The insulator 42 is interposed between the stator core 41and the coil 43, thereby preventing the electrical short circuit betweenthe stator core 41 and the coil 43.

The circuit board 24 is positioned below the stator 23 and above thebase member 21. The circuit board 24 extends annularly around thebearing housing 22 and perpendicularly to the center axis 9. The circuitboard 24 carries an electric circuit on at least one of the uppersurface and the lower surface thereof. An end of the conducting wireforming each of the coils 43 is electrically connected to the electriccircuit on the circuit board 24 with a terminal pin (not illustrated)interposed therebetween. When electric power is supplied to the circuitboard 24 from an external power source, a driving current is suppliedfrom the electric circuit on the circuit board 24 to the plurality ofcoils 43.

The mold resin portion 25 covers the stator core 41, the insulator 42,the plurality of coils 43, and the circuit board 24. The mold resinportion 25 is made of, for example, thermosetting unsaturated polyesterresin. The mold resin portion 25 is obtained by injecting molten resininto a cavity provided in a mold in which the base member 21, thebearing housing 22, the stator 23, and the circuit board 24 are placedand then curing the resin. That is, the mold resin portion 25 isintegrated with the base member 21, the bearing housing 22, the stator23, and the circuit board 24 into a single molded resin component byresin molding.

Since the stator 23 and the circuit board 24 are covered with the moldresin portion 25 as described above, the contact of water drops with thestator 23 and the circuit board 24 is suppressed. Accordingly, theoccurrence of malfunctions of the electric elements in the motor 1 thatmay be attributed to the contact with water drops is suppressed. Notethat part of the surface of the stator 23 may be exposed from the moldresin portion 25. For example, the radially outer end surface of each ofthe teeth 412 and the inner peripheral surface of the insulator 42 maybe exposed from the mold resin portion 25. In such a case, the radiallyouter end surface of each of the teeth 412 and the inner peripheralsurface of the insulator 42 only need to be covered with an insulatingcoating. Thus, even if those surfaces are exposed from the mold resinportion 25, the occurrence of malfunctions attributed to the contactwith water drops is suppressed.

The upper bearing 26 and the lower bearing 27 form a mechanism thatsupports a shaft 31, to be described below, such that the shaft 31 isrotatable. The lower bearing 27 is interposed between a lower endportion of the shaft 31 and the bearing housing 22. The upper bearing 26is positioned above the lower bearing 27 and is interposed between theshaft 31 and the bearing housing 22. The upper bearing 26 and the lowerbearing 27 are each, for example, a ball bearing including an inner raceand an outer race that are rotatable relative to each other with the aidof balls. The outer race of the upper bearing 26 and the outer race ofthe lower bearing 27 are fixed to the inner peripheral surface of thebearing housing 22. The inner race of the upper bearing 26 and the innerrace of the lower bearing 27 are fixed to the outer peripheral surfaceof the shaft 31. Hence, the shaft 31 is supported in such a manner as tobe rotatable about the center axis 9 and relative to the bearing housing22.

Alternatively, the upper bearing 26 and the lower bearing 27, which areball bearings, may be replaced with bearings of another type.

The rotor unit 3 includes the shaft 31, a rotor holder 32, and aplurality of magnets 33.

The shaft 31 is a columnar member extending along the center axis 9. Theshaft 31 is made of metal such as stainless steel. A portion of theshaft 31 including the lower end thereof is positioned on the radiallyinner side with respect to the bearing housing 22. The upper end of theshaft 31 projects upward above the bearing housing 22 and the stator 23.The shaft 31 is rotatably supported by the upper bearing 26 and thelower bearing 27.

The rotor holder 32 is a member that rotates with the shaft 31. Therotor holder 32 is made of metal such as iron, which is a magneticmaterial. The rotor holder 32 includes a holder top-plate portion 321and a holder cylindrical portion 322. The holder top-plate portion 321extends substantially perpendicularly to the center axis 9. A centralportion of the holder top-plate portion 321 is fixed to the shaft 31.The holder cylindrical portion 322 extends downward from the outerperiphery of the holder top-plate portion 321 and in a cylindricalshape.

The plurality of magnets 33 are fixed to the inner peripheral surface ofthe holder cylindrical portion 322. The radially inner surface of eachof the magnets 33 forms an N- or S-pole face. The plurality of magnets33 are arranged in the peripheral direction such that the N-pole facesand the S-pole faces are positioned alternately. The radially outer endsurfaces of the respective teeth 412 face the radially inner surfaces ofthe respective magnets 33 in the radial direction.

To drive the motor 1, a driving current is supplied from the circuitboard 24 to the coils 43 through the terminal pins. Then, a rotatingmagnetic field is generated around the plurality of teeth 412 of thestator core 41. Thus, a torque acting in the peripheral direction isgenerated between the teeth 412 and the magnets 33. Consequently, therotor unit 3 rotates about the center axis 9.

The axial-flow fan 100 includes an impeller 5. The impeller 5 includesan impeller cup 51 and a plurality of blades 52. The impeller cup 51 isfixed to the rotor holder 32. The plurality of blades 52 extend radiallyoutward from the outer peripheral surface of the impeller cup 51. Whenthe motor 1 is driven, the rotor unit 3 rotates together with theimpeller 5. Thus, air currents flowing from the upper side toward thelower side are generated around the axial-flow fan 100.

Now, a process of forming the mold resin portion 25 will be described indetail. FIG. 2 is a flow chart illustrating the process of forming themold resin portion 25. FIGS. 3 to 5 illustrate different states in theprocess of forming the mold resin portion 25.

First, an assembly 20 including the base member 21, the bearing housing22, the stator 23, and the circuit board 24 is prepared. Then, theassembly 20 is placed between a first mold 61 and a second mold 62.Specifically, referring to FIG. 3, the base member 21 is fitted into thefirst mold 61 such that the lower surface and the outer peripheralsurface thereof are in contact with the first mold 61, whereby the basemember 21 is supported by the first mold 61 (step S1). Then, referringto FIG. 4, upper part of the assembly 20 is covered with the second mold62 as illustrated in FIG. 4, whereby the pair of molds 61 and 62 arejoined (step S2). Accordingly, a cavity 60 is provided between the firstmold 61 and the second mold 62 that have been joined. The assembly 20 ispositioned in the cavity 60.

Subsequently, molten resin is injected into the cavity 60 (step S3). Asrepresented by broken lines in FIGS. 4 and 5, the second mold 62 has agate 63 serving as a supply port from which the molten resin isinjected. The molten resin is injected into the cavity 60 from theoutside of the first mold 61 and the second mold 62 through the gate 63.When the molten resin has spread all over the cavity 60 as illustratedin FIG. 5, the molten resin is cured by heating or the like (step S4).The molten resin thus cured serves as the mold resin portion 25. Themolten resin is injected into the cavity 60 with a predeterminedpressure by an injection-molding device. By the injection with thepredetermined pressure, the molten resin can spread evenly all over thecavity 60. The injection method is not limited to such a method. Themolten resin may be injected into the cavity 60 by another method,instead of using the injection-molding device.

Subsequently, the first mold 61 and the second mold 62 are undone, andthe assembly 20 now having the mold resin portion 25 thereon is removedfrom the first mold 61 and the second mold 62 (step S5).

FIGS. 6 and 7 are vertical sectional views of relevant part of the motor1 and illustrate the base member 21, the circuit board 24, the firstmold 61, and the second mold 62. FIG. 6 illustrates a state before thefirst mold 61 and the second mold 62 come into contact with each other.FIG. 7 illustrates a state after the first mold 61 and the second mold62 have come into contact with each other.

As illustrated in FIG. 6, the base member 21 is provided in advance witha projection 70. The projection 70 projects upward from the uppersurface of the outer wall portion 213. In plan view, the projection 70is positioned on the radially outer side with respect to the circuitboard 24. The projection 70 according to the embodiment has an annularshape that is centered at the center axis 9.

When the first mold 61 and the second mold 62 are joined together, thelower surface of the second mold 62 is pressed against the projection70. Hence, as illustrated in FIG. 7, the projection 70 is squashed.Since only the projection 70 among various portions of the base member21 is intentionally squashed, the load applied to the other portions ofthe base member 21 is reduced. Consequently, the occurrence of damage tothe disc portion 211, the inner wall portion 212, and the outer wallportion 213 of the base member 21 under the load applied from the secondmold 62 is suppressed.

In particular, in the embodiment, the outer wall portion 213 having anannular shape is provided on the upper surface of the base member 21.Hence, the peripheral edge portion of the base member 21 has higherrigidity than in a case where the outer wall portion 213 is notprovided. Therefore, the occurrence of damage to the base member 21under the load applied from the second mold 62 is further suppressed.

The projection 70 does not overlap the circuit board 24 in the axialdirection. Furthermore, the projection 70 and the circuit board 24 arenot directly connected to each other. Hence, the load applied from thesecond mold 62 to the projection 70 is less likely to be transmitted tothe circuit board 24. Therefore, the occurrence of deformation of thecircuit board 24 under the load from the second mold 62 is suppressed.

Referring to FIG. 6, the projection 70 that is yet to be squashed has,at the radial center thereof, a top 701 where the thickness thereof inthe axial direction is largest. The second mold 62 comes into contactwith the top 701 of the projection 70. Hence, the load from the secondmold 62 is locally applied to a region of the projection 70 that isaround the top 701. Therefore, the projection 70 is squashed easily.

Referring to FIG. 7, the projection 70 squashed by the second mold 62 isdenoted as a projection resultant 71. Hence, a finished motor 1 has theprojection resultant 71 on the upper surface of the outer wall portion213 of the base member 21. In plan view, the projection resultant 71 ispositioned on the radially outer side with respect to the circuit board24. FIG. 8 includes a top view and a vertical sectional view of afinished base member 21. As illustrated in FIG. 8, the projectionresultant 71 according to the embodiment has an annular shape that iscentered at the center axis 9.

In step S3 described above, the projection 70 has a function ofpreventing the molten resin from leaking toward the radially outer side.The mold resin portion 25 is positioned on the radially inner side withrespect to the outer edge of the projection 70. As illustrated in FIG.6, in the embodiment, the projection 70 is positioned in such a manneras to overlap, in the axial direction, an inner periphery 621 of thelower end surface of the second mold 62. Hence, in plan view, the outerperiphery of the mold resin portion 25 overlaps at least part of theprojection resultant 71.

If the entirety of the projection 70 is positioned on the radially outerside with respect to the inner periphery 621 of the lower end surface ofthe second mold 62, a small gap is provided between the base member 21and the second mold 62 on the radially inner side with respect to theprojection 70. Hence, the finished motor 1 is supposed to have a thinresin film on the radially inner side with respect to the projectionresultant 71. Such a thin film tends to peel off the base member 21. Incontrast, in the structure according to the embodiment, no such thinresin film is formed on the radially inner side with respect to theprojection 70.

As illustrated in FIG. 6, the projection 70 according to the embodimentis positioned at a distance from and on the radially inner side withrespect to a peripheral edge 215 of the upper surface of the base member21. Accordingly, the projection resultant 71 obtained when theprojection 70 is squashed is also positioned at a distance from and onthe radially inner side with respect to the peripheral edge 215 of theupper surface of the base member 21. If the projection 70 is provided atthe very outer edge of the upper surface of the base member 21, part ofthe projection 70 that is squashed may be pushed into the gap betweenthe first mold 61 and the second mold 62. In such an event, the firstmold 61 and the second mold 62 do not completely come into surfacecontact with each other, resulting in a possible cause for reducedaccuracy in the molding of the mold resin portion 25. In contrast, inthe structure according to the embodiment, the projection 70 that issquashed may spread slightly in the radially outer side but is lesslikely to be pushed into the gap between the first mold 61 and thesecond mold 62. Hence, the upper end surface of the first mold 61 andthe lower end surface of the second mold 62 can be accurately broughtinto contact with each other.

According to the embodiment, as represented by the broken lines in FIGS.4 and 5, the second mold 62 has the gate 63 as described above. The gate63 extends through the second mold 62 from the outer peripheral surfaceto the inner peripheral surface within part of the second mold 62 in theperipheral direction. Hence, as illustrated in FIG. 1, the finished moldresin portion 25 has a gate resultant 251 as a resultant of the gate 63on part of the outer peripheral surface thereof. The gate resultant 251is positioned below the circuit board 24 in the axial direction andabove the base member 21 in the axial direction.

Since the gate 63 is provided at the above-described position, thecavity 60 can be filled with the resin without generating bubbles nearvarious electronic components mounted on the circuit board 24.Furthermore, the gate resultant 251 is positioned below the rotor unit 3and the impeller 5. Therefore, the gate resultant 251 can be preventedfrom interfering with the rotor unit 3 or the impeller 5.

The gate may alternatively be provided in the first mold 61. Forexample, the base member 21 may have a through hole extendingtherethrough in the axial direction, and a gate may be provided at aposition of the first mold 61 that faces the through hole in the axialdirection. In such a case, a gate resultant is formed at a position ofthe lower surface of the mold resin portion 25 that is within thethrough hole of the base member 21 in plan view.

While an exemplary embodiment of the present disclosure has beendescribed above, the present disclosure is not limited to the aboveembodiment.

FIG. 9 is a vertical sectional view of relevant part of a motor 1Aaccording to a modification. FIG. 10 includes a top view and a verticalsectional view of a base member 21A according to the modification. Inthe modification illustrated in FIGS. 9 and 10, the base member 21A hastwo projection resultants 71A. The two projection resultants 71A eachhave an annular shape that is centered at a center axis 9A. The twoprojection resultants 71A have different diameters. With a plurality ofsuch annular projection resultants 71A arranged concentrically andhaving different diameters, the leakage of molten resin toward theradially outer side in the process of forming the mold resin portion canfurther be suppressed.

The details in the shape of each of the members may be different fromthose illustrated in the drawings provided for the present disclosure.

The present disclosure is applicable to, for example, a stator unit, amotor, and a method of manufacturing a stator unit.

Features of the above-described preferred embodiments and themodifications thereof may be combined appropriately as long as noconflict arises.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A stator unit included in a motor, the statorunit comprising: a base member extending substantially perpendicularlyto a center axis extending vertically; an armature positioned above thebase member; a circuit board positioned above the base member andelectrically connected to the armature; and a mold resin portioncovering the armature and the circuit board, wherein the base member hasa projection resultant on a radially outer side with respect to thecircuit board in plan view; and the projection resultant is positionedon a radially inner side with respect to a peripheral edge of an uppersurface of the base member.
 2. The stator unit according to claim 1,wherein the projection resultant has an annular shape that is centeredat the center axis, and wherein the mold resin portion is provided on aradially inner side with respect to an outer edge of the projectionresultant, with an outer periphery of the mold resin portion overlappingat least part of the projection resultant in plan view.
 3. The statorunit according to claim 2, wherein the projection resultant is one of aplurality of projection resultants provided on the base member, andwherein the plurality of projection resultants are centered at thecenter axis and have different diameters.
 4. The stator unit accordingto claim 1, wherein the base member has an annular wall portion on anupper surface, and wherein the projection resultant is positioned on anupper surface of the wall portion.
 5. The stator unit according to claim1, wherein the mold resin portion has a gate resultant on an outerperipheral surface.
 6. The stator unit according to claim 5, wherein thegate resultant is positioned below the circuit board in an axialdirection and above the base member in the axial direction.
 7. Thestator unit according to claim 1, wherein the mold resin portion has agate resultant on a lower surface.
 8. The stator unit according to claim7, wherein the base member has a through hole extending through the basemember in the axial direction, and wherein the gate resultant isprovided at a position of the lower surface of the mold resin portionthat is within the through hole in plan view.
 9. The stator unitaccording to claim 1, wherein the base member has an annular shape,wherein the stator unit further includes a bearing housing provided onan inner side of the base member and extending vertically in acylindrical shape, wherein the armature is fixed to an outer peripheralsurface of the bearing housing, and wherein the base member ispositioned below the armature and is fixed to the outer peripheralsurface of the bearing housing.
 10. The stator unit according to claim9, wherein the bearing housing is made of metal.
 11. The stator unitaccording to claim 9, wherein the bearing housing is made of resin. 12.A motor comprising: the stator unit according to claim 1; and a rotorunit supported in such a manner as to be rotatable about the center axisand having pole faces that each face the armature in a radial direction.